A fire has killed at least 19 people in an illegal six-storey plastics market in the Indian city of Kolkata, police have said.

The blaze, which started before 4am, was likely caused by a short circuit, West Bengal fire minister Javed Khan said.

Toxic gases released by the blaze hampered rescue efforts at what Mr Khan called "an illegal, unauthorised market".

The victims were porters working in the market

Police were looking for the owner of the building, which was filled with dozens of small shops selling various plastic products and warehouses on the upper floors, where chemicals and paper were stored.

Another 10 people are in hospital in a critical condition and the death toll was expected to rise, Mr Khan said.

Police said the victims were porters working in the market, who also slept there at night and 18 of the dead were men.

Toxic gases were released by the blaze

Residents said the market had been operating in the building, which only has one entrance, for nearly 40 years.

Mamata Banerjee, the state's top elected official, who visited the site soon after the blaze was brought under control, issued an ultimatum to the building's owners to install fire safety equipment within two months.

Ms Banerjee said the previous government that ruled the state for more than three decades had allowed the building to operate without any permits or safety measures.

Firemen try to douse the fire at the market

In December 2011, at least 93 people died in a deadly fire in a hospital in Kolkata.

Soon after that, Ms Banerjee promised that her government would crackdown on lax safety procedures in public buildings.

Safety regulations are routinely ignored in India, where fire stairways and evacuation drills are rare.

A woman reacts as she watches her shop burn

Even if fire extinguishers are present, they are often several years old and almost never serviced.